A new microscopy of atomic motion in nanostructures

We propose to develop a new method to obtain direct space images, with ~30 nm resolution, of the atomic motion in GaN nanostructures. This new microscopy is based on the combination of Coherent Diffraction Imaging (to obtain direct space images) and resonant elastic scattering at forbidden reflections, which provides sensitivity to atomic motion, and is becoming possible thanks to the extreme brilliance of the new source. After a very promising first experiment, we would like to continue our investigation GaN nanopillars, where free surfaces, strain, crystal defects and inversion domain boundaries are expected to cause inhomogeneities of the atomic thermal motion. A first real space image was obtained by CDI at a forbidden reflection at room temperature. More time is requested to repeat the measurement at high temperature, to enhance the relative contribution of atomic thermal motion over the intrinsic local anisotropy of the crystal structure.

我们拟开发一种全新方法，以实现约30纳米分辨率的直接空间成像，用于观测氮化镓（GaN）纳米结构中的原子运动。该新型显微技术结合了相干衍射成像（Coherent Diffraction Imaging，用于获取直接空间图像）与禁反射处的共振弹性散射——后者可实现对原子运动的灵敏探测，而新型光源的超高亮度使这一技术成为可能。在完成极具前景的首轮实验后，我们计划继续对氮化镓纳米柱展开研究，该结构的自由表面、应变、晶体缺陷以及反相畴界，预计会引发原子热运动的不均匀性。此前，研究团队已在室温下通过禁反射处的相干衍射成像获取了首张实空间图像。我们申请追加实验时长，以在高温下重复该测量，从而提升原子热运动相对于晶体结构本征局部各向异性的相对贡献。